University of Linköping, Dept. of Mathematics
Linköping with about 120 000 inhabitants, is situated 200 km south of Stockholm. One can fly to Stockholm or Copenhagen and take a connecting flight to Linköping or Norrköping (40 km from Linköping). There are airport taxis from Norrköping to Linköping, which should be reserved in advance. If you arrive at the airport in Linköping, the most convenient to reach your hotels is by taxi. There is also a bus service from the airport.
Linköping is also on the main railway between Copenhagen and Stockholm, 2-2 1/2 hours from Stockholm and 6-7 hours from Copenhagen. If you fly to Stockholm (Arlanda) and wish to continue by train, then you should take the airport bus from Arlanda to the Central Station of Stockholm (about 40 km and 40 minutes). When you arrive to Linköping by train, the most convenient way most of the hotels is to take a taxi. There is a special telephone at the taxi-rank that you can use to order a cab.
The temperature in Linköping in January can be anything between +5C (40F) and -20C (-10F). Be prepared for the worst.
More info on Linköping is available.